You're paying the capital and maintenance costs of the fossil plants whether you have solar or not. They are not "driving up the price" because they're not new.
And in the real world renewables will never go to zero so you can reduce that cost when you build a lot of renewables, even accounting for the worst case winter.
Am I saying that overbuilding solar from a financial perspective never happens? No. But I am saying that if money is your priority, it's straightforward to plan and build renewables in a way that strictly saves you money. Even though you'll sometimes be paying people to do nothing!
And in the real world renewables will never go to zero so you can reduce that cost when you build a lot of renewables, even accounting for the worst case winter.
Am I saying that overbuilding solar from a financial perspective never happens? No. But I am saying that if money is your priority, it's straightforward to plan and build renewables in a way that strictly saves you money. Even though you'll sometimes be paying people to do nothing!